A total of 23,101 murder investigations were opened in the first 11 months of this year, surpassing the 22,409 registered in the whole of 2011, figures published on Friday night by the interior ministry showed. The figures go back to 1997.

Pena Nieto took office in December 2012 pledging to tame the violence that escalated under his predecessor Felipe Calderon. He managed to reduce the murder tally during the first two years of his term, but since then it has risen steadily.

At 18.7 per 100,000 inhabitants, the 2017 Mexican murder rate is still lower than it was in 2011, when it reached almost 19.4 per 100,000, the data showed. The rate has also held below levels reported in several other Latin American countries.

According to U.N. figures used in the World Bank's online database, Brazil and Colombia both had a murder rate of 27 per 100,000, Venezuela 57, Honduras 64 and El Salvador 109 in 2015, the last year for which data are available.